1. Field of the Invention
The present invention relates generally to a power-saving relay control system having a minimum number of parts, and more particularly to a relay control system for controlling a bi-stable latch-type relay.
2. Description of the Related Art
Commonly, relays having low voltage and small current characteristics must, in addition to supplying sufficient operating current, reserve holding current after operation to maintain relay contact for a specified period of time. As shown in FIG. 3a, a DC or AC power source and an inverter circuit I have been utilized to activate relay M when a Set pulse is at its maximum electric potential. In the case of a non-latch-type relay, relay M fails to maintain operation unless inverter I has been furnished with a high electric potential. Therefore, relay M continues to consume power. If a latch-type relay is used, resetting the relay is impossible after a set operation.
Turning to FIG. 3B, the addition of an independent Set Rely M1 and a Reset relay M2 is known for a latch-type relay, where M1 and M2 are given set and reset pulses, respectively, from separate control circuits. In such a circuit, a separate power source and control circuit must be included, and power must be continuously applied during operation of the relays.
In addition to the prior art need for overly sophisticated and non-economic use of circuit elements combined with large electric and thermal power consumption, the prior art relay control circuits are difficult to implement in conventional data communication switching equipment or remote control equipment where no appropriate power supply can be readily accessed.